These resources coupled with the size of the country and the total freedom of interaction and mobility of scientists,has brought American science to preeminence in many fields of science during the third quarter of this century.

• 这些财力和物力的投资，加上这个国家的幅员辽阔和科学家们充分的自由交往和自由流动，使美国在本世纪第三个25年期间在许多科学领域内成就非凡。